Roofing Underlayments

Our dome roof designs utilize more insulation, provide for roof ventilation, incorporate long-lasting roof coverings and tend to have longer construction cycles.  The many variables that contribute to roof top temperatures; insulation, facing, pitch, color, etc., make it difficult to predict what kind of heat profile the roof top will experience.  Choosing an underlayment that will perform under all of these demanding conditions is essential to a successful roof design.

We DO NOT recommend the use of 15# or 30# regular felt roofing paper anymore.  Grace Tri-Flex is a far superior product to standard felt paper and it weighs less than 30# for a 1000 sf roll (the equivalent of 5 rolls of felt paper).

Building codes require the use of a “water and ice protection” roofing underlayment in various parts of the roof. We specify the use of Grace Ice and Water Shield Membrane because it has a 250% to 300% elongation quality and fantastic adhesion. It's rubberized asphalt seals around nails and provides a level of protection that traditional felt underlayments just can't match.  We use their HT (High temperature) version for valley flashing, the very top of the dome and as an “extended” flashing around our skylights and cupolas.

Grace TRI-FLEX®
Grace TRI-FLEX® is an innovative spunbonded polypropylene coated with a layer of U.V. stabilized polypropylene on both sides.  This technology, available only from Grace, creates a very durable and tough weather resistant fabric.  It has excellent tear resistance, designed to withstand even the strongest wind conditions.  It is inorganic, contains no asphalt, and is up to 15 times more resistant to tearing than 30# felt. Lightweight and easy to install. Remains pliable at temperatures as low as -60°F (-51°C) and weighs only 30 lbs. Thermal stability up to 240°F (116°C).  Tri-Flex and Tri-Flex Extreme have a permeability rating of .04, so it is considered a vapor barrier. Depending on climate zone and insulation type, you may need to ventilate below the exterior plywood roof triangles.

Grace TRI-FLEX® Extreme™
Grace Tri-Flex® Xtreme™ is an innovative synthetic roofing underlayment featuring an advanced skid-resistant technology. It provides a superior walking surface in both dry and wet conditions on steep-slope applications. The product is extremely strong, durable, lays flat and is easy to install. It provides outstanding water-shedding protection to the roof and thus
represents the next generation in synthetic roofing underlayments.

Grace Ice & Water Shield®
Grace Ice & Water Shield® is a premier self-adhered membrane composed of two waterproofing materials - an aggressive rubberized asphalt adhesive backed by a layer of high density cross laminated polyethylene.  The rubberized asphalt surface is backed with a foldless release paper that protects its adhesive quality.  During application, the release paper is easily removed, allowing the rubberized asphalt to bond tightly to the roof deck.  In addition, embedded in the membrane is a split release on demand feature called Ripcord®.  Thermal stability up to 180°F (82°C).

Grace Ice & Water Shield® HT
We use Ice & Water Shield HT as a flashing and waterproofing membrane around our skylights, venting products, cupola roofs, valley flashing and on other portions of the dome roof subject to wind driven rain or low slopes. It is a premier self-adhered membrane designed to deliver premium in-place performance for high temperature applications. For desert and high mountain areas with hot summers, see below. Grace Ice & Water Shield® HT is a premier self-adhered membrane designed to deliver premium in-place performance for high temperature applications.  It is composed of two waterproofing materials - an innovative and proprietary rubberized asphalt adhesive combined with a high performance polymeric film with UV barrier properties.  Thermal stability up to 240°F (116°C).

Grace Ice & Water Shield® Ultra
Grace Ultra is designed to protect sloped roofs from the effects of wind driven rain and ice dams in applications where the self adhered membrane must withstand high, in-service temperatures for extended periods of time.  This membrane offers excellent performance at elevated temperatures, in hot desert southwest climates or any application where superior heat resistance is a requirement. We use Ultra as the flashing around our skylights, venting products, cupola roofs, valley flashing and on other portions of the dome roof in the climate zones mentioned. Thermal stability up to 300°F (149°C).

Grace Bituthene waterproofing membrane
We use Bituthene waterproofing on all our Permanent Wood Foundation Systems. We also use it on some low slope roof areas not subject to heat buildup by the sun. Bituthene is a self-adhesive, cold-applied sheet membrane consisting of a top surface of high strength, 4 mil. cross laminated, high density polyethylene film adhered to 56 mils of rubberized asphalt. Rubberized asphalt promotes full adhesion to the substrate while simultaneously providing crack-bridging and crack-cycling properties. This 60 mil thick membrane is supplied in 36" wide rolls 66.7' long inter-wound with a disposable coated paper release sheet.  Thermal stability is up to 135°F (57°C).

Select the correct Grace Underlayment for your climate zone:

Where winters are generally mild but will still experience wind driven rain,  Grace Tri-Flex® can offer sufficient protection.

In mild winter climates, if it is expected that the roof will be subjected to  high temperatures for extended periods of time, then Grace Ice & Water Shield Ultra  should be the product of choice.

In areas of the country that experience snowy winters, especially with wind driven rain and snow, Grace Ice & Water Shield® would provide maximum protection.

In snowy winter climates, if it is expected that the roof will be subjected to  very high temperatures for extended periods of time, then Grace Ice & Water Shield® HT (high temperature) should be the product of choice. 

If using metal roofing (such as Reinke Aluminum Shakes) ) use Grace HT.  In high altitudes, or in hot desert areas, use Grace Ultra under the Reinke shakes. These roofs can reach extremely high temperatures due to low reflectivity, high absorption, and high conductivity of the metals. 

For more Frequently Asked Questions regarding these Grace products, click here.

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